Can you charge an electric car with solar? The real maths

Q: What happens when the sun is not shining?

The car charges from the grid, exactly as it does today. Solar supplements your grid use rather than replacing it entirely. Even in cloudy northern Europe, a well-timed charging schedule can shift a significant portion of annual EV energy onto solar: the share that falls naturally in daytime hours. Load-shifting like daytime EV charging can lift a home's solar self-consumption well above the ~30% baseline, even without a battery.

Yes. A typical home solar array produces more than enough energy to cover average annual driving, but only if you line up when you charge with when the sun shines. A car doing 10,000–15,000 km a year needs roughly 2,000–3,000 kWh, well within what a 5 kWp roof produces in most of Europe. The gap to close is timing, not generation capacity.

You park the car at night and plug it in. The sun set hours ago. So the honest first answer is: your panels charge your car only if you make the numbers line up on purpose. Once you see the maths, you can.

How much energy one charge actually needs

Start with the car, not the panels. Real-world electric cars average about 19–21 kWh per 100 km in European conditions, based on analysis of 342 models available in Europe (MDPI/Sustainability, 2024). That is roughly 0.19–0.21 kWh per kilometre. The figure of 0.18 kWh/km is towards the efficient end of the certified WLTP range; real-world use lands closer to 0.20 kWh/km.

The EU average car travels around 10,900 km per year (Eurostat passenger mobility data). A driver covering 12,000 km burns roughly 2,400 kWh; at 15,000 km it rises to about 3,000 kWh. Pull your own annual mileage from the dashboard and multiply by 0.20. That one number drives everything below.

Picture it as a tank you top up daily. A 60 kWh battery sounds large, but a 40 km commute pulls back only about 8 kWh. You refill a glass, not the reservoir.

If you drive in miles: the same logic holds at around 0.32 kWh per mile, so 9,000 miles a year lands near 2,900 kWh, or about 8 kWh on an average day.

How much your panels make in a day

A 1 kWp array does not make 1 kWh every hour. It hits that rate at peak sun only. What counts is the daily total across the full year, and that depends on where your roof sits.

The PVGIS tool from the EU Joint Research Centre calculates irradiance for your exact coordinates using satellite data going back to 2005. As a rough guide, one installed kWp delivers per day, averaged over the year:

Location	Annual yield (kWh/kWp)	Average daily output per kWp
Madrid / southern Spain	~1,500–1,600	~4.1–4.4 kWh
Northern Germany	~950–1,100	~2.6–3.0 kWh
Edinburgh / Scotland	~800–900	~2.2–2.5 kWh
Sydney / Brisbane	~1,400–1,700	~3.8–4.7 kWh

A common 5 kWp home array in Madrid makes around 20–22 kWh on an average day. Your 8 kWh of daily driving sits comfortably inside that. In Edinburgh the same array makes roughly 11–12 kWh. Still plenty for the car alone, but you share it with the heat pump, the kettle, and everything else in the house.

These are annual averages. Winter days in Edinburgh can dip to 2–3 kWh total from the whole array; a summer day in Madrid can reach 30 kWh. The calculator uses your coordinates and the full PVGIS monthly profile, not just the annual mean.

The catch: when the car is home and when the sun is up

Solar peaks at midday. Most cars sit in an office car park at midday and come home after dark. Plug in at 7 pm and you charge from the grid, regardless of how good your roof is. The energy your panels made at noon went to the grid hours earlier.

Three moves fix the timing.

Charge during daylight. If you work from home, or the car sits on the drive on weekends, set the charger to run from late morning to mid-afternoon. This is the cleanest, cheapest charge you will get: straight from the roof, no losses.
Shift the load with a timer. Most home chargers and most modern EVs let you schedule charging. On a sunny forecast, set the next day's charge for the solar window rather than overnight.
Store the surplus. A home battery banks your midday excess and releases it into the car at night. It works, but you pay for the battery and accept a round-trip loss of typically 5–12% for modern LFP systems (AC-to-AC efficiency 88–95%), so it rarely pays back on EV charging alone (Sunlit Energy, 2026). We cover when storage earns its keep in When a solar battery actually pays off.

How many extra panels an EV actually needs

Here the maths gets friendly. To cover about 8 kWh of daily driving in a sunny climate where each kWp makes ~4.2 kWh, you need roughly 2 kWp of extra panels (four or five standard 400 W panels). In Edinburgh, where each kWp makes ~2.3 kWh on average, the same daily driving needs about 3.5 kWp, or nine panels.

Add around 30% for real-world losses: weather variation, the timing gap between solar peak and charging, and inverter losses. That gives you roughly six panels in Madrid and twelve in Edinburgh to cover average driving on top of the house load. A smaller number than most people expect.

The incremental cost matters too. Residential installation costs vary by country (see our country-specific data in how much solar panels cost in 2026): as a guide, UK installers typically quote £900–1,500/kWp, Eurozone countries run €900–1,800/kWp (SurgePV, 2026), the US sits around $2.50–3.50/W, and Australia around A$0.9–1.5/W. Adding a few panels to an existing install often costs less per watt than the original system, because you already paid for the scaffolding, the inverter headroom, and the electrician's day.

When solar EV charging actually pays: a cost comparison

Here is what a kWh costs from each source in 2026:

Source	Typical cost per kWh	Notes
Solar (self-consumed)	~€0.06–0.14	Residential rooftop LCOE range for Germany; efficient/high-yield systems reach the lower end (Fraunhofer ISE, July 2024)
Grid at home (Germany)	€0.37	BDEW 2026
Grid at home (UK)	£0.28	Ofgem price cap Jan–Mar 2026
Grid at home (Spain)	€0.21	Eurostat H2-2025 all-in
Public rapid charger (DC fast)	€0.50–0.80	Eleport Europe 2025

Every kWh you move from a public rapid charger onto your own roof saves €0.45–0.75 (or the local equivalent). Drive 12,000 km a year at 0.20 kWh/km and you use about 2,400 kWh for the car. Shift half onto solar and you save roughly 20–30% of your annual electricity bill against grid rates, or a larger share against public rapid charging. Use the calculator for a figure in your currency.

The payback on incremental EV panels often beats the payback on the original system. We show the honest payback period, NPV, and IRR for your specific roof, tariff, and country in our solar payback and IRR guide.

Step-by-step: making solar EV charging work

Find your daily driving kWh. Odometer reading ÷ 365, multiply by 0.20 kWh/km (or 0.32 per mile).
Check your location yield. Use PVGIS or our calculator to get kWh/kWp/day for your roof.
Calculate extra kWp needed. Daily driving kWh ÷ daily kWh per kWp, then add 30% for losses.
Get a marginal quote. Ask your installer for the cost of adding those extra panels to your existing system, not a full re-quote.
Set up daytime charging. Programme your charger to run 10 am–3 pm on sunny-forecast days, even before the panels arrive.

Frequently asked questions

Can I charge my EV entirely from solar panels?

Yes, over the course of a year. A 5–6 kWp array in central Europe produces more than enough for average driving (10,000–15,000 km). The practical challenge is daily timing: solar peaks at midday; most cars charge at night. A timer, a flexible work-from-home schedule, or a home battery closes the gap.

How many solar panels do I need to charge an electric car?

For typical European driving (about 12,000 km/year, ~2,400 kWh), you need roughly 2–4 extra kWp beyond your household needs, depending on location. In southern Europe that is five to seven standard 400 W panels; in northern Europe, eight to twelve. Our calculator gives a location-specific figure.

Is it cheaper to charge an EV from solar or from the grid?

Substantially cheaper from solar. Grid electricity in Germany costs around €0.37/kWh in 2026 (BDEW); public rapid charging runs €0.50–0.80/kWh (Eleport). The lifetime cost of generating your own solar electricity typically falls between €0.06 and €0.14/kWh for residential rooftop systems in Germany, with efficient/high-yield installs at the lower end (Fraunhofer ISE, July 2024). The exact figure depends on your system cost and local yield.

What happens when the sun is not shining?

The car charges from the grid, as it does today. Solar supplements your grid use rather than replacing it entirely. Even in cloudy northern Europe, a well-timed charging schedule can shift a significant portion of annual EV energy onto solar: the share that falls naturally in daytime hours. Load-shifting like daytime EV charging can lift a home's solar self-consumption well above the ~30% baseline, even without a battery.

Do I need a special charger to charge an EV from solar?

Not necessarily. Any home EVSE (wallbox) works. Solar-aware chargers from brands like Zappi or SolarEdge can throttle charge rate to track surplus solar output in real time, which increases direct solar use and reduces grid draw. They cost more upfront but pay back if your car is often home during the day.

So yes, you can charge an electric car with solar. The panels you need are fewer than most brochures suggest, the savings against public charging are large, and the payback on incremental panels is often the best return on your roof. Run your own numbers rather than trusting a range estimate.

Estimate your roof →

Estimate only, not a quote. Figures use local climate data and average tariffs; your installer's quote will be exact.